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Online shopping: Better for the environment?

December 16, 2011 | 7:07
am

With just nine days to go before Christmas, we've all got our lists. We've been checking them twice. And now comes the naughty or nice part, at least environmentally: Deciding whether to buy that Nerf gun in person or online.

More shoppers are doing the latter. About 4.2% of purchases are now done with a computer or hand-held device, compared with 3.3% in 2008, according to the U.S. Census Bureau. What about all the cardboard boxes and foam peanuts that come with the growing number of online purchases? And how about those delivery trucks idling at the curb? Is online shopping better for the environment, or could it be worse?

According to a study from Pittsburgh's Carnegie Mellon University, online shopping is almost always less energy-intensive than going to a store in person.

“E-commerce is the less energy-consumptive option approximately 80% of the time,” according to the report, which cited customer transportation to and from a brick-and-mortar store as the single most important factor. More energy is used in transportation than in packaging, warehousing and personal computing, as well as in running retail stores and data centers. That may seem counterintuitive, considering the fuel efficiency of delivery trucks and the packaging that arrives on shoppers' doorsteps, but on average, e-commerce uses about 30% less energy than traditional retail, according to the study.

Coauthor Chris Hendrickson said he was most surprised by “how small an impact packaging really has, particularly with the growth of recycling channels for packaging.”

Although packaging accounts for 22% of the carbon dioxide emissions of an item purchased online, customer transportation accounts for 65% of emissions when buying the equivalent item at a retail store, according to the study, conducted by Carnegie Mellon's Green Design Institute.

The research cited statistics from the Department of Transportation, which found that most Americans make a round trip of 14 miles when they shop. It also presumed a passenger vehicle with an average fuel economy of 22 miles per gallon, based on U.S. Environmental Protection Agency data, and an average of 1.5 items purchased per shopping trip, according to the National Highway Traffic Safety Administration.

Delivery trucks account for just 32% of the CO2 emissions of an e-commerce purchase; trucks drop off one package for every 0.1 to 1 mile traveled, according to interviews with delivery truck drivers cited in the Carnegie Mellon study.

Neither Federal Express nor United Parcel Service were able to provide a packages-delivered-per-mile figure, but in 2010, UPS said it used 0.117 gallons of fuel to deliver each package. Using the DOT, EPA and NHTSA figures cited in the study, an average of 0.636 gallons of gas would be used to pick up that package with a passenger car.

Since the Carnegie Mellon research was published in 2008, Hendrickson said, variables in the equation continue to change, but the basic findings remain valid. “There have been a lot of changes happening that affect the relative costs and relative benefits of online versus in-store shopping,” he said this week, most of which continue to tip the scales in favor of e-commerce.

Hendrickson, a professor of engineering at Carnegie Mellon, cited the tendency of brick and mortar retailers to overstock items, such as books, that are ultimately returned, adding to their carbon footprint. The bankruptcy of companies such as Borders and store closures by retail giants such as the Gap also are prompting shoppers to drive farther, he said.

Though fuel standards are rising for passenger vehicles, they also are rising for heavy duty trucks. UPS said the fuel efficiency of its deliveries increased 3.3% just from 2009 to 2010, and FedEx is upgrading its delivery fleet with compressed natural gas, hybrid-electric and pure-electric vehicles.

When Hendrickson first began looking into the environmental impacts of e-commerce 10 years ago, he said, companies such as Amazon were mostly shipping packages via air, which is six to 13 times more energy intensive than shipping via truck, according to a 2006 report in the International Journal of Life-cycle Assessment. Most companies now offer multiple delivery options. About 12% of packages were sent via air freight at the time of the 2008 study. The other 88% were sent over land, according to delivery data from the study's retail partner, Buy.com. Still, the study found that e-commerce packages shipped by plane were likely to generate fewer greenhouse gas emissions than picking up the same item from a store in a car.

The Carnegie Mellon study compared the environmental impact of purchasing a single 1-pound item online or at a store. The study did not look at the energy impacts of manufacturing the item or delivering it to its first storage warehouse, since those activities were presumed equal regardless of how the item was bought. For objects that do not use energy during their lifetimes, such as books, clothes and food, manufacturing is the most energy-intensive part of their life, accounting for about 90% of their overall carbon footprint, Hendrickson said.

Customers who want to make the right environmental choice may want to consider buying less, buying used, buying online or, if they shop at brick-and-mortar retail, controlling the environmental impact of transporting those items home. Hendrickson suggested shoppers combine trips or, if possible, walk, bicycle or take public transit rather than drive.